On Tue, Mar 17, 2020 at 08:37:47AM +0100, Heinrich Schuchardt wrote: > On 3/17/20 3:12 AM, AKASHI Takahiro wrote: > > There are platforms on which OS's won't be able to access UEFI variables > > at runtime (i.e. after ExitBootServices). > > With this patch, all the UEFI variables are exported as a configuration > > table so as to enable retrieving variables' values from the table, and > > later modifying them via capsule-on-disk if necessary. > > I do not understand why we should expose our internal memory for holding > UEFI variables to the operating system. This might end up in users > trying to access the variables directly.
I think that you somehow misunderstand my code as it never exposes any "internal memory," although I don't know what it exactly means in this context. This configuration table is nothing but a list of data that represent all the UEFI variables in implementation-agnostic format. > I do not understand why we should not keep the pointer in our private > memory. Anyway, this patch naively implements Peter's proposal while I also submitted another patch[1] that allows HL-OS to use GetVariable interface directly via *caching*. Since how we should enable accessing UEFI variables at runtime is one of key issues, I'd rather discuss in boot-arch ML as I suggested in the cover letter. I have already re-activated the discussion there[2]. Please make your comments there for wider audience. [1] https://lists.denx.de/pipermail/u-boot/2019-June/371769.html [2] https://lists.linaro.org/pipermail/boot-architecture/2020-March/001149.html Thanks, -Takahiro Akashi > Best regards > > Heinrich > > > > > The idea is based on Peter's proposal[1] in boot-arch ML. > > > > [1] > > https://lists.linaro.org/pipermail/boot-architecture/2018-October/000883.html > > > > Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org> > > --- > > include/efi_loader.h | 7 +++ > > lib/efi_loader/Kconfig | 10 ++++ > > lib/efi_loader/efi_boottime.c | 10 ++++ > > lib/efi_loader/efi_capsule.c | 4 ++ > > lib/efi_loader/efi_variable.c | 109 ++++++++++++++++++++++++++++++++++ > > 5 files changed, 140 insertions(+) > > > > diff --git a/include/efi_loader.h b/include/efi_loader.h > > index 79bdf9586d24..93ed5502821c 100644 > > --- a/include/efi_loader.h > > +++ b/include/efi_loader.h > > @@ -183,6 +183,8 @@ extern const efi_guid_t efi_guid_hii_string_protocol; > > extern const efi_guid_t efi_guid_capsule_report; > > /* GUID of firmware management protocol */ > > extern const efi_guid_t efi_guid_firmware_management_protocol; > > +/* GUID of runtime variable access */ > > +extern const efi_guid_t efi_guid_variable_storage; > > > > /* GUID of RNG protocol */ > > extern const efi_guid_t efi_guid_rng_protocol; > > @@ -659,6 +661,10 @@ efi_status_t EFIAPI efi_query_variable_info( > > u64 *remaining_variable_storage_size, > > u64 *maximum_variable_size); > > > > +#ifdef CONFIG_EFI_VARIABLE_EXPORT > > +efi_status_t efi_install_variables_table(void); > > +#endif > > + > > /* > > * See section 3.1.3 in the v2.7 UEFI spec for more details on > > * the layout of EFI_LOAD_OPTION. In short it is: > > @@ -683,6 +689,7 @@ struct efi_load_option { > > void efi_deserialize_load_option(struct efi_load_option *lo, u8 *data); > > unsigned long efi_serialize_load_option(struct efi_load_option *lo, u8 > > **data); > > efi_status_t efi_bootmgr_load(efi_handle_t *handle); > > +efi_status_t efi_install_variables_table(void); > > > > /* Capsule update */ > > efi_status_t EFIAPI efi_update_capsule( > > diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig > > index 616e2acbe102..edb8d19059ea 100644 > > --- a/lib/efi_loader/Kconfig > > +++ b/lib/efi_loader/Kconfig > > @@ -41,6 +41,16 @@ config EFI_SET_TIME > > Provide the SetTime() runtime service at boottime. This service > > can be used by an EFI application to adjust the real time clock. > > > > +config EFI_VARIABLE_EXPORT > > + bool "Export variables table as configuration table" > > + depends on !EFI_VARIABLE_RUNTIME_ACCESS > > + depends on EFI_CAPSULE_UPDATE_VARIABLE > > + default y > > + help > > + Select this option if you want to export UEFI variables as > > + configuration table so that OS can still get UEFI variable's > > + value. > > + > > config EFI_DEVICE_PATH_TO_TEXT > > bool "Device path to text protocol" > > default y > > diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c > > index c2a789b4f910..406644e4da67 100644 > > --- a/lib/efi_loader/efi_boottime.c > > +++ b/lib/efi_loader/efi_boottime.c > > @@ -2898,6 +2898,16 @@ efi_status_t EFIAPI efi_start_image(efi_handle_t > > image_handle, > > if (ret != EFI_SUCCESS) > > return EFI_EXIT(EFI_INVALID_PARAMETER); > > > > +#ifdef CONFIG_EFI_VARIABLE_EXPORT > > + /* Install variables database as a configuration table */ > > + ret = efi_install_variables_table(); > > + if (ret != EFI_SUCCESS) > > + return EFI_EXIT(ret); > > +#endif > > + /* > > + * TODO: remove a table after image is terminated. > > + */ > > + > > image_obj->exit_data_size = exit_data_size; > > image_obj->exit_data = exit_data; > > > > diff --git a/lib/efi_loader/efi_capsule.c b/lib/efi_loader/efi_capsule.c > > index 1293270aea95..6b737aec1b28 100644 > > --- a/lib/efi_loader/efi_capsule.c > > +++ b/lib/efi_loader/efi_capsule.c > > @@ -18,7 +18,11 @@ static const efi_guid_t > > efi_guid_firmware_management_capsule_id = > > EFI_FIRMWARE_MANAGEMENT_CAPSULE_ID_GUID; > > const efi_guid_t efi_guid_firmware_management_protocol = > > EFI_FIRMWARE_MANAGEMENT_PROTOCOL_GUID; > > +#ifdef CONFIG_EFI_VARIABLE_EXPORT > > +const efi_guid_t efi_guid_variable_storage = EFI_VARIABLE_STORAGE_GUID; > > +#else > > static const efi_guid_t efi_guid_variable_storage = > > EFI_VARIABLE_STORAGE_GUID; > > +#endif > > > > /* for file system access */ > > static struct efi_file_handle *bootdev_root; > > diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c > > index c316bdfec0e4..270e5211f633 100644 > > --- a/lib/efi_loader/efi_variable.c > > +++ b/lib/efi_loader/efi_variable.c > > @@ -641,3 +641,112 @@ efi_status_t efi_init_variables(void) > > { > > return EFI_SUCCESS; > > } > > + > > +#ifdef CONFIG_EFI_VARIABLE_EXPORT > > +/** > > + * efi_install_variables_table() - install variables table > > + * > > + * This function adds a configuration table that contains all the cache > > + * data of UEFI variables for runtime access. > > + * > > + * Return: status code > > + */ > > +efi_status_t efi_install_variables_table(void) > > +{ > > + u16 var_name16[64]; > > + efi_uintn_t var_name16_len; > > + efi_guid_t guid; > > + u32 attributes; > > + struct efi_capsule_header capsule; > > + u8 *data = NULL, *p; > > + efi_uintn_t capsule_size; > > + struct efi_ebbr_variable variable; > > + u8 *var_buf; > > + efi_uintn_t var_size, var_max_size; > > + efi_status_t ret; > > + > > + capsule.capsule_guid = efi_guid_variable_storage; > > + capsule.header_size = sizeof(capsule); > > + capsule.flags = CAPSULE_FLAGS_POPULATE_SYSTEM_TABLE; > > + capsule_size = sizeof(capsule); > > + > > + /* Determine size of capsule */ > > + var_name16[0] = 0; > > + var_name16_len = 64; > > + var_buf = NULL; > > + var_max_size = 0; > > + for (;;) { > > + ret = EFI_CALL(efi_get_next_variable_name(&var_name16_len, > > + var_name16, > > + &guid)); > > + if (ret == EFI_NOT_FOUND) > > + break; > > + else if (ret != EFI_SUCCESS) > > + goto out; > > + > > + var_size = 0; > > + ret = EFI_CALL(efi_get_variable(var_name16, &guid, &attributes, > > + &var_size, var_buf)); > > + if (ret != EFI_BUFFER_TOO_SMALL) > > + goto out; > > + > > + capsule_size += sizeof(variable) + var_size; > > + if (var_size > var_max_size) > > + var_max_size = var_size; > > + } > > + capsule.capsule_image_size = capsule_size; > > + > > + ret = efi_allocate_pool(EFI_RUNTIME_SERVICES_DATA, > > + capsule_size, (void **)&data); > > + if (ret != EFI_SUCCESS) > > + return EFI_OUT_OF_RESOURCES; > > + > > + var_buf = malloc(var_max_size); > > + if (!var_buf) { > > + ret = EFI_OUT_OF_RESOURCES; > > + goto out; > > + } > > + > > + /* Copy data */ > > + p = data; > > + memcpy(p, &capsule, sizeof(capsule)); > > + p += sizeof(capsule); > > + > > + var_name16[0] = 0; > > + for (;;) { > > + ret = EFI_CALL(efi_get_next_variable_name(&var_name16_len, > > + var_name16, &guid)); > > + if (ret == EFI_NOT_FOUND) > > + break; > > + else if (ret != EFI_SUCCESS) > > + goto out; > > + > > + var_size = var_max_size; > > + ret = EFI_CALL(efi_get_variable(var_name16, &guid, &attributes, > > + &var_size, var_buf)); > > + if (ret != EFI_SUCCESS) > > + /* should not happen */ > > + goto out; > > + > > + u16_strcpy(variable.variable_name, var_name16); > > + variable.vendor_guid = guid; > > + variable.attributes = attributes; > > + variable.data_size = var_size; > > + > > + memcpy(p, &variable, sizeof(variable)); > > + p += sizeof(variable); > > + memcpy(p, var_buf, var_size); > > + p += var_size; > > + } > > + > > + ret = EFI_CALL(efi_install_configuration_table( > > + &efi_guid_variable_storage, data)); > > + > > +out: > > + free(var_buf); > > + if (ret != EFI_SUCCESS && data) > > + efi_free_pool(data); > > + > > + return ret; > > +} > > +#endif /* CONFIG_EFI_VARIABLE_EXPORT */ > > >
